How to make countour edges
As a lazy solution which also needs some clearing work, use Offset Edges addon. See how to install addon to access its functionality.

First, for it to work properly, apply scale for the object (Ctrl+A > Scale) and remove doubles (W > Remove Doubles).

With that, run Ctrl+E > Offset Edges > Offset (or Extrude, depending on whether you want the extruded edges to be connected to original ones or not).
It won't work well in the corners because of big amount of vertices there. You might need to edit that by using e.g. Vertex Slide tool to grab vertices along the edges to get rid of distorted corners.





Repeat the same for yet one more concentric iteration.

This will be easier if you dissolve that big amount of vertices before using the addon with Limited Dissolve (not an option if those vertices are needed as details).